Just go to Norway in the summer then (our winter). The temperatures are comparable to ours, maybe you can convince her because it'd be winter here but summer there.
Yeah man, it was almost 30 in Bergen last week. 23 in Oslo...and even at 18 degrees here it's nice and hot. Perfect for being outside.
I want to really go and visit Norway (preferably do a boat cruise through Scandinavia).
You should give the Hurtigruten a try. In summer you'll experience the midnight sun and if you go in winter they'll give you a free ticket if you DONT see northern lights during the cruise.
http://www.hurtigruten.com/en/norway-voyages/